Update.. VW checked the heating systems and found no fault.
Dispite the option to check or uncheck 'auto supplementary heater ' via the head unit, it seems the VW build code label which is stuck on the inside of the service booklet, does not show the code for the heater. Conclusion... one not fitted.
ED: https://www.ebay.co.uk/itm/122967206482/
However the NOx code remained and the sensor was changed.
In the past 3 weeks, the NOx and DPF differential seniors have been changed under warranty, which could have been a huge bill !!!!
Last edited by Uwe; 11-14-2019 at 12:34 PM. Reason: Added link